The objectives of this proposal are twofold: (1) to evaluate the barrier function of the airway mucosa with particular attention to elucidating pathways and mechanisms for uptake and transport of large polar solutes across the epithelial barrier, and (2) to investigate the biochemical pathogenesis of emphysema using the blotchy mouse model. The first objective will be accomplished by a combined morphologic and physiologic study of the bidirectional movement of a series of polar solutes covering a range of molecular weights across the tracheal epithelium in vitro employing Ussing-like tubular chambers. Transcellular and paracellular pathways of horseradish peroxidase uptake will be assessed by transmission electron microscopy and tight junctional configuration evaluated by freeze etching. Using physical and chemical stimuli in "normal" guinea pig trachea, we will partition overall transport of large polar solutes into the paracellular and transcellular components and also elucidate the quantitative relationship between goblet cell number and their secretory activity and large solute permeability. Finally, we will evaluate the effects of immediate allergic reaction and squamous metaplastic changes on large solute permeability. These studies may enhance our knowledge of the protective barrier function of the airway mucosa and cellular and subcellular factors that regulate movement of exogenous and endogenous macromolecules across the airway epithelia. The overall objective of the second part of the proposal is to study lung connective tissue injury and the role of deficiency of the copper dependent enzyme, lysyl oxidase in pathogenesis of emphysema, utilizing the blotchy mouse. Specifically, we will focus on the biochemical basis for the extreme susceptibility of the blotchy mouse to the development of emphysema following inhaled oxidant pollutant exposure. These studies may enhance our understanding of the role of inherited abnormalities on connective tissue synthesis in the pathogenesis of emphysema following environmentally induced proteolytic lung injury.